calendar won't delete event from invitees phone

So I created an event, invited my husband's email and then realized the dates were wrong (event in calendar lasts 40 days, but actually it's just 2 hours..haha). I corrected it on my phone but it won't update on his phone. I deleted the event completely on my phone but yet it's still on his phone. How do I delete this off of his phone? It's probably a simple fix, but I'm fairly iPhone incompetent.